The Irish name of Crookhaven is Cruachan and it lies on the peninsula of the Mizen or in Irish, Ivagha. Cruachan possibly means "the little rick" or "little hillock" and perhaps comes from a geographical feature of the landscape.
The English name of Crookhaven is generally believed to derive from Sir Thomas Crooke, who is also associated with the English settlement in Baltimore in the early 1600's.
The earliest record of the locality is found in 1199 in the Decretal Letter of Pope Innocent III, "Celmolaggi" is listed and Bolster (1972) identifies it with Crookhaven. There is also reference to the church being dedicated to St Molaggi, who came from Fermoy in the 7th century. He was the Patron Saint of "Tegh-Molagga" now Timoleague, Co Cork.
There was a 15th century O' Mahony castle in Crookhaven. The exact location is not now known. In 1700 Bishop Downes describes "the walls of an old castle about the middle of the town which they say was formerly a prison."
Around 1620 Sir Richard Boyle, the Earl of Cork, and Sir William Hull of Leamcon, developed pilchard fisheries in Crookhaven.
A Star-shaped fort was built in 1622 by Sir Thomas Roper and depicted on Downe Survey (1652) map in the vicinity of the village. The exact location is not known as no remains survive.
There are the remains of the 1852 copper mines near the tip of the Crookhaven Peninsula. The circular magazine built on crest of ridge is in good shape. The lower courses of the engine house remains. Further to the west is the remains of another magazine which was part of the mining complex.